Miniature relay with double air gap magnetic circuit

ABSTRACT

A MINIATURE RELAY IS PROVIDED INCLUDING A STURDY, BOXLIKE ELECTROMAGNET UNIT MOUNTED IN SPACED RELATION TO A BASE. ONE SIDE OF THE BOX-LIKE STRUCTURE INCLUDES FIRST AND SECOND POLE PIECES MAGNETICALLY CONNECTED TO THE SOURCE OF ELECTROMAGENTIC ENERGY. AN ARMATURE UNIT WHICH COMPRISES AN ARMATURE AND A CONTACT ACTUATING LEVER ARM IS MOUNTED FOR ROTATION ABOUT AN AXIS EXTERIOR TO THE DIMENSIONS OF THE ARMATURE. THE ARMATURE IS FREE OF ENGAGEMENT WITH THE POLE FACES WHEN THE ELECTROMAGNETIC ENERGY SOURCE IS DEENERGIZED. WHEN THE SOURCE IS ENERGIZED, THE ARMATURE MOVES THROUGH THE AIR GAPS BETWEEN ITSELF AND THE FIRST AND SECOND POLE PIECES RESPECTIVELY. ONE FACE OF THE ARMATURE CONTACTS BOTH POLE PIECES, CLOSING THE MAGNETIC CIRCUIT BETWEEN THEM. IN ONE FORM, THE POLE PIECES HAVE SURFACES IN A COMMON PLANE.

Jan. 5, 1971 ZMMER 3,53,612

MINIATURE RELAY WITH DOUBLE AIR GAP MAGNETIC CIRCUIT Filed May 21, 1969 4 Sheets-Sheet 1 llVl/E/VTOR JOHN S ZIMMER HIS ATTORNEY J. S. ZIMMER Jan. 5, 1971 MINIATURE RELAY WITH DOUBLE AIR GAP MAGNETIC CIRCUIT Filed May 21, 1969 4 Sheets-Sheet 2 HIS ATTORNEY Jan. 5, 1971 J, g Z|MMER 3,553,612

MINIATURE RELAY WITH DOUBLE AIR GAP MAGNETIC CIRCUIT Filed may 21, 1969 4 Sheets-Sheet :5

'Q" mfvmrofi. JOHN s. ZIMME HIS ATTORNEY J. S. ZIMMER Jan. 5," 1971 MINIATURE RELAY WITH DOUBLE AIR GAP MAGNETIC CIRCUIT 4 Sheets-Sheet 4 Filed May 21, 1969 //VVE/VT0/?. JOHN S. ZIMMER HIS ATTORNEY United States Patent U.S. Cl. 335-128 32 Claims ABSTRACT OF THE DISCLOSURE A miniature relay is provided including a sturdy, boxlike electromagnet unit mounted in spaced relation to a base. One side of the box-like structure includes first and second pole pieces magnetically connected to the source of electromagnetic energy. An armature unit which comprises an armature and a contact actuating lever arm is mounted for rotation about an axis exterior to the dimensions of the armature. The armature is free of engagement with the pole faces when the electromagnetic energy source is deenergized. When the source is energized, the armature moves through the air gaps between itself and the first and second pole pieces respectively. One face of the armature contacts both pole pieces, closing the magnetic circuit between them. In one form, the pole pieces have surfaces in a common plane.

BACKGROUND OF THE INVENTION This invention relates to relays, More specifically, it relates to relays which may be compactly constructed.

The use of miniaturized relays has become increasingly important in recent years. One application in which they are especially useful is where weight and space are a premium, such as in aircraft instrumentation. Requirements for successful operation in aircraft include small size, light weight, and reliability under adverse vibration conditions. In order to construct a reliable miniature relay, it is not sufficient to construct the components of the relay so that they are smaller than components of prior relays. Maximum advantage must be taken of the electrical and mechanical operating characteristics of the relay components.

In a typical standard or miniature relay, a coil and a core are magnetically connected in series with pole pieces to attract an armature. When the coil is energized, the armature moves to close the magnetic circuit between the pole pieces and become magnetically connected in series with the core. Contact actuating means are mechanically coupled to the armature, and when the armature is moved by magnetic attraction to the core, the switching function of the relay is performed. Implicit in this basic operation of a relay are factors which contribute to relay size. One major factor is the size of the gap through which the armature must travel to become magnetically connected in series with the core. This distance must be sufficient so that the cont-act actuating means mechanically coupled to the armature travel the necessary distance to move the contact from one position to another. If a relay is built so that the armature moves through a small air gap upon energization of the coil, the armature, and the contact actuating means must provide a suflicient mechanical advantage so that the contact actuating means moves through a distance sufficient to actuate the contacts. The magnetic field produced by the coil must be powerful enough to attract the armature in such an arrangement.

In a relay, a small air gap not only provides the advantage of compactness, but also provides for optimum use of the magnetic power developed by the coil. Since attraction of an armature to a magnet versus distance from the magnet is an inverse square relationship, the closer an armature is maintained to a magnetic circuit, the more strongly it is attracted.

While strides have been made toward decreasing the air gap between an armature and pole faces in prior miniature relays, this feature of relay design has not been optimized. In any application in which any desired air gap is to be maintained between an armature and pole faces, it is desirable that close tolerances in relay con struction be maintained in mass'production.

It is also desirable to maintain the armature in place as rigidly as possible once the coil is energized in order to keep the relay contacts closed when ,the coil is energized. This is facilitated by the use of a double magnetic air gap arrangement. In the great majority of prior art relays, a single gap arrangement is employed in which one end of the armature is always magnetically connected to the core. In a double gap arrangement, the armature is free of engagement with the pole pieces when the coil is deenergized. When the coil is energized, first and second pole pieces magnetically connected to opposite sides of the core attract the armature through first and second air gaps.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a miniature relay of a construction in which close tolerances may be maintained in mass production.

It is a more specific object of the present invention to provide a miniature relay in which the armature operates through a very small air gap.

It is another object of the present invention to provide a miniature relay which is rugged and simple in construction and efiicient in operation.

It is also an object of the present invention to provide a miniature relay in which a high mechanical advantage may be obtained due to the construction of an armature and contact actuating means.

It is a further object of the present invention to provide an improved relay construction.

Briefly stated, there is provided in accordance with one embodiment of the present invent-ion a miniature relay capable of being mass produced in which an armature is operated through a desired air gap which may be minimized. A base on which contacts are mounted supports a box-like electromagnet unit including end plates which form opposite sides of the box-like structure. Pole pieces are magnetically and mechanically integral with the end plates and project into the space between them. A coil and a core, mounted to magnetically connect the end plates and provide electromagnetic energy. An armature, which is free of engagement with the pole faces of the pole pieces when the coils deenergize, is mounted to close the magnetic circuit between the pole faces when the coil is energized. In one form of the invention the faces of the pole pieces facing the armature have surfaces formed to define a plane. The armature has corresponding portions formed in a plane so that when the coil is energized, the opposing portions of the pole pieces and the armature come into contact over their entire opposing surface area.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects and features of novelty which characterize the present invention are pointed out with particularity in the claims forming the concluding portion of the specification. The invention, both as to its organization and manner of operation, as well as further objects and advantages attained with its use may be further understood by reference to the following description taken in connection with the drawings.

In the drawings:

FIG. 1 is an exploded view of a relay constructed in accordance with the present invention;

FIG. 2 is a plan view of the relay of FIG. 1;

FIG. 3 is a partial right side view of the relay of FIG. 1 showing details of the pivot support means;

FIG. 4 is an elevation of the embodiment shown in FIG. 1 (shown in phantom on FIG. 4) partially broken away to reveal details of the armature biasing arrangement and further partially broken away to reveal details of the contact actuating mechanism;

FIG. 5 is a partial left side view of the relay as seen in FIG. 3 showing details of the armature stop arrangement;

FIG. 6 is a partial elevation of a further embodiment of the present invention; and

FIG. 7 is a partial isometric view of FIG. 6 illustrating details of the armature supporting means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded view of a relay constructed in accordance with the present invention. In the other figures, which point out details of the construction, the same reference numerals refer to the same components. A base 10 is provided which may conveniently be rectangular in shape, and the preferred embodiment supports the con tacts in relay structure. A channel 11 may be formed in the upper surface of the base 10 spaced from its perimeter for receiving a cover 12 (shown in cross-section in FIG. 4) for hermetically sealing the relay. The base 10 carries contact sets 15 as well as internal and external leads and contacts therefor. The relay structure, briefly stated, further includes an electromagnetic unit 20, which provides electromagnetic energy and an armature unit 25, which is operated by the electromagnetic unit to actuate the contact sets 15.

The armature unit is preferably L-shaped and includes an armature portion 26 having a face 27 which contacts the energized electromagnet unit 20. The armature unit 25 further includes and rotates with shaft 29 having an axis of rotation which is exterior to the dimensions of the armature 26. The shaft 29 is received in suitable bearings and support means described below. As the armature unit 25 rotates, a contact actuating portion 31 included at the end of an elongated lever arm 28, extending from the portion of the armature unit 25 adjacent the shaft 29, actuates the contact sets 15 in a conventional manner.

Features of interest to be described below include the maintenance of a minimum air gap between the armature 26 and electromagnet unit 20 and the formation of a planar surface in the side of the electromagnetic unit 20 which opposes the armature face 27.

A significant feature of the present invention is the sturdy, box-like construction of the electromagnet unit 20, which may be best understood with reference to both FIG. 1 and the plan view of FIG. 2. The box-like electromagnet unit 20 is maintained in spaced relation to the base 10 by any suitable means. The suitable means of the present embodiment comprises a plurality of posts 35, each of which is mounted opposite a corner of the electromagnet unit 20 and are supported in the base 10.

A pair of magnetically conductive end plates and 42 form first and second opposite sides of the box-like structure. First and second pole pieces 44 and 46 extend respectively from edges of the end plates 40 and 42 into the space between them to form a portion of the third side of the box-like structure. The pole pieces 44 and 46 are magnetically conductive and also preferably integrally formed with and perpendicular to the end plates 40 and 42, respectively. It is this third side of the box which the face 27 of the armature 26 contacts when electromagnet unit is energized. The pole piece 44 has a front face 41 facing the armature 26 and a rear face 45. Similarly the pole piece 46 has a front face 43 and a rear face 47.

The third side of the box-like structure is completed by a first non-magnetic spacing means which comprises a backup plate 51 which is preferably of the same vertical dimensions as the pole pieces 44 and 46 and secured to their rear faces and 47. The box-like structure is completed by a second non-magnetic spacing means comprising a stop plate 52 mounted to the edges of the end plates 40 and 42 remote from the pole pieces 44 and 46.

Electromagnetic energy is provided by a coil unit 55 which is mounted on a core 56 and mounted between the end plates 20. The coil 55 is positioned between the end plates 40 and 42 and the core 56 is received in apertures 57 and 58, respectively formed in the end plates 40 and 42.

A pair of leads 60 and 61 extend from the coil to appropriate terminals on the base 10 to provide for energization of the electromagnet unit.

In the unit thus described, the pole face 41, end plate 42, core 56, and pole face 43 are all magnetically connected in series. When the coil 55 is energized, the flux emanating from the pole faces 41 and 43 causes the attraction of armature 26 through the first and second air gaps between it and the pole faces 41 and 43, respectively so that when the armature face 27 contacts the pole faces 41 and 43, the armature 26 completes the magnetic circuit therebetween. This arrangement is thus a double air gap magnetic circuit.

A significant feature of the present arrangement lies in the fact that the backup plate 51 and stop plate 52 prevent relative movement between the pole pieces 44 and 46 and the end plates 40 and 42. Thus when the electromagnet unit 20 is energized and the armature face 27 rests against the pole faces 41 and 43, there will be no movement of the pole pieces 44 and 46 and end plates 40 and 42 tending to dislodge the armature 26 from its position even under adverse vibration conditions. In addition, since the electromagnet unit 20 comprises a unitary, box-like structure, it may be conveniently handled in mass production for manufacture to close tolerances. It should be noted that in the present construction, the coil unit 55 and core 56 may be inserted in the electromagnet unit 20 after remainder of the box-like structure has been assembled, further facilitating ease of manufacture.

A further feature of the present arrangement is the maintenance of a small air gap between the armature face 27 and the pole faces 41 and 43. While the armature unit 25 may be supported in any convenient manner, it is desirable to provide an arrangement in which the smallest buildup of tolerances during assembly is provided. Therefore, in the present embodiment, the armature unit 25 is mounted to the electromagnet unit 20. For this reason, a substantially U-shaped pivot support means (shown assembled in FIG. 3) 65, constructed of non-magnetic material, is provided. A transverse portion 66 is secured to the lower edge of the pole pieces 44 and 46 and bearing support portions 67 and 68 extend downwardly from its ends. The shaft 29 of the armature unit 25 is journaled in the bearings 67A and 68A.

In order to provide for maximum compactness of the relay, the armature unit 25 is mounted so that the armature face 27 faces the pole faces 41 and 43 and the elongated lever arm 28 extends between the base 10 and the electromagnet unit 20. The contact actuating portion 31 is located at the end 30 of the lever arm 28 so that the maximum mechanical advantage from the rotation of the armature unit 25 and shaft 29 in bearings 67A and 68A is obtained.

The armature 26 is forced free of engagement with the pole faces 41 and 43 when the coil 55 is deenergized, by contact restoring forces and a biasing means 70 constructed in accordance with the present invention to be described below. Also, upon energization of the coil 55, diversion of magnetic flux lines through portions of the armature 26, which would weaken its attraction to the pole faces 41 and 43, is prevented.

The requisite minimum distance which must be maintained between the armature face 27 and the pole faces 41 and 43 is that which is necessary to prevent any projecting imperfections from the surface of either of those elements from contact with the other. This requisite distance may be minimized in accordance with the present invention by forming the pole faces 41 and 43 to have surfaces in a common plane, forming a planar surface on the armature face 27, and aligning the armature 26 so that its face 27 contacts the pole faces 41 and 43 in the common plane. This planar arrangement is further advantageous in that it permits a maximum surface area of contact of the armature 26 and electromagnet unit 20 so as to minimize the effective reluctance of the magnetic circuit. Furthermore the magnetomotive force 6? supplied from the electromagnet is most efficiently utilized as seen from the equation:

where is the flux available in the air gap, R is the closed gap reluctance (which can be minimized by ample pole and armature face geometry), x is the gap between the armature and pole faces and A is the effective area of the opposing faces. Large values of x serve to reduce available flux for an available According to Maxwells law the force When is reduced (for an increasing x and a given (:7) the force required to do the required mechanical work is rapidly diminished with large air gaps. For the foregoing reasons, the use of small air gaps is desirable. This further assures that the electromagnet unit 20 is sufficently strong to operate the armature unit 25 which has a large mechanical advantage due to the short travel of the armature 26 and the longer travel of the elongated lever arm 28. The box-like structure of the electromagnet unit 20 facilitates its handling during the formation of the common plane of the pole faces 41 and 43, which may, for example, be accomplished by electrolytic grinding.

Referring now to FIGS. 1 and 4, the biasing means 70 comprises a substantially V-shaped non-magnetic, that is, a high magnetic reluctance, spring positioned in the space between the backup plate 51 and the armature 26. The spring 70 includes a first leg 71 having projections 73 and 74, which are received in an aperture 75 formed in the center portion of the backup plate 51 and a second leg 72 including a portion abutting the armature face 27. Firm anchoring of the spring 70 is provided by the projections 73 and 74, which secure it against up and down movement. By making leg 71 extend beyond projections 73 and 74, the extension 71A and leg 71 are flat and by positioning 71 and 71A flush with the backup plate 51, rotational movement of the spring 70 about an axis drawn through the length of the leg 71 or an axis drawn across the spring at the intercept of projections 73- and 74 and the beginning of extension 71A is prevented even under adverse vibration conditions. The design provides freedom from spring rotation in two dimensions and freedom of lineal spring movement in two dimensions. The present construction obviates the need for welding the spring 70 in place. Not only does this provide convenience in assembly, but, since welding tends to change spring characteristics, uniformity of spring operation over a large number of relays is maintained, The compressible V-shaped spring thus is self-retaining by friction and compression forces by resort to mechanical projections, positioning, etc. and provides a fixed bias to hold the armature lever arm and contact actuator away from the contacts when the coil is deenergized and the structure is shocked.

The present invention also conveniently provides for limiting the distance of the armature 26 from the deenergized electromagnet 20 to maintain the desired minimal air gap. As stated above, and as illustrated in FIGS. 1, 4,

and 5, in the preferred form, lever arm 28 extends below the electromagnet unit 20. The elongated lever arm 28 is arranged so that its end 30 moves up toward the stop plate 52 as the armature 26 moves away from the electromagnet unit 20. In order to limit the upward motion of the lever arm 28 and thus determine the air gap, an arm 81 integrally formed with the stop plate 52, extends from its lower portion and includes a stop which is positioned to engage the lever arm 28. The stop plate 52 and arm 81 are preferably constructed of a substantially nondeformable material so that the position of the arm 81 may be adjusted to determine the desired air gap and, once set, remain in position.

For a better understanding of the present invention, it should be noted that the above-described construction is markedly different from other arrangements in which small air gaps are maintained. In the common rotary armature arrangement, two pole pieces, which are roughly analogous to the pole pieces 44 and 46, are supported above a base and an armature is pivoted around a vertical axis which lies in the center of the space between the pole pieces. The rotary armature closes the magnetic circuit between them by contacting the front face of one pole piece and the rear face of the other. In such an arrangement, the faces of the pole pieces which contact the armature do not lie in the same plane and are not susceptible to a single machining operation by which a surface for armature seating is provided, Similarly, armature faces lie in two planes rather than one.

In accordance with a further embodiment of the invention, illustrated in FIGS. 6 and 7, an armature unit is provided which is similar to the armature unit 25 but does not include the shaft 29. The armature unit 125 is supported in the same spaced relation to the electromagnet unit 20 by an armature unit support hinge 132 rather than a pivot support means 65. The armature unit support hinge 132 is a substantially L-shaped hinge member having a first leg 135 secured to the electromagnet unit 20 at a point below the pole pieces 44 and 46 and a second leg 136 secured to the armature 126. The leg 135 is sandwiched between non-magnetic supporting bracket 137. Bracket 137 is attached to and positioned transverse of the lower edges of the pole pieces 44 and 46 and also to a non-magnetic support piece 138 by welding. The leg 136 is sandwiched between face 127 of the armature 126 and a support piece 139, and secured to the armature face 127. While the support hinge 132 could itself be welded in place, use of the support pieces 138 and 139 are provided to obviate the need for welding of the support hinge 132 itself so as not to deleteriously change its spring characteristics.

The armature unit support hinge 132 is deformable in response to the magnetic force exerted by the electromagnet unit 20 on the armature 126. When the coil 55 is energized, the armature unit 125 rotates about an axis external to the dimensions of the armature 126 so that the armature face 127 engages the pole faces 41 and 43 in the desired manner. In using the spring hinge, the spring is deformable and serves to act as the restoring force in lieu of spring 70 of FIG. 1 and does align and maintain position of the armature 125 with respect to magnetic unit 20.

While preferred forms of the invention have been shown and described in detail, and various alternatives have been stated, the specification has been written with a view toward enabling those skilled in the art to make many modifications consistent with the scope of this invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A miniature relay comprising:

(a) a base supporting at least one pair of operable contacts;

(b) first and second magnetic end plates forming opposite sides of a box-like structure and first and second magnetic pole pieces projecting respectively from said first and second end plates into the space between them, said pole pieces having front faces and rear faces and upper and lower edges above and below the front and rear faces;

(c) means for providing electromagnetic energy mounted between said end plates, and means comprising a core magnetically connected in series with said end plates and a coil mounted on said core;

(d) an armature unit comprising an armature and an elongated lever arm, said armature having a face for mating with the front faces of said first and second pole pieces through respective air gaps and said elongated lever arm having a portion for operating said contacts;

(e) nonmagnetic means for maintaining said end plates and pole pieces in spaced relation; and

(f) means for supporting said armature so that said armature rotates about an axis external to the area defined by said armature and transverse of said front faces in response to said provided electromagnetic energy so that the face of said armature mates with front faces of said first and second pole pieces to close the magnetic circuit therebetween.

2. A miniature relay according to claim 1 wherein said non-magnetic means comprises a first spacing means constructed of non magnetic material for maintaining said pole pieces in spaced relation, said first spacing means being positioned so as to leave the front faces of said pole pieces uncovered, and a second spacing means constructed of non-magnetic material for maintaining the edges of said end plates away from said pole pieces in spaced relation.

3. A miniature relay according to claim 2 wherein the front faces of said first and second pole pieces are formed so as to be in a common plane and the face of said armature includes a surface formed to define a plane, said armature being aligned to contact said pole pieces in the common plane.

4. An arrangement according to claim 2 further comprising:

a substantially V-shaped non-magnetic resilient biasing means positioned in the space between said first spacing means and said armature for biasing said armature to a position of angular rotation about said axis so as to be free of engagement with said pole pieces.

5. A miniature relay according to claim 4 wherein:

(a) said first spacing means comprises a backup plate extending across the space between said pole face pieces and being secured at its ends to the rear faces of said pole pieces and having an aperture formed in its central portion; and

(b) the first leg of said biasing means is flat and rests against said backup plate and extends above said aperture for preventing rotation of said biasing means and further includes a projection being received in said aperture for retaining said biasing means in place, whereby relative movement between said resilient biasing means and said backup plate is prevented.

6. An arrangement according to claim 2 wherein said supporting means comprises a substantially U-shaped bearing support constructed of non-magnetic material having a transverse portion mounted to the lower edges of said pole pieces parallel to the axis of rotation of said armature and first and second arms projecting downwardly from the ends thereof, each of the arms including a bearing, and a shaft secured to said armature unit, the end of said shaft being received in said bearings.

7. arrangement according to claim 2 wherein said supportmg means comprises hinge means consisting of a substantially L-shaped member constructed of non-magnetic material and having a first leg supported to the lower edges of said pole pieces and a second leg secured to said armature unit, said armature unit being aligned with respect to said hinge means and spring biased thereby so that the face of said armature is maintained in spaced relation with said pole faces when said coil is deenergized, said armature responsive to said provided electromagnetic energy when said coil is energized to deform said hinge and permit the face of said armature to contact the front faces of said pole pieces.

8. A miniature relay according to claim 2, wherein said lever arm is mounted for motion between said electromagnet unit and said base and said second spacing means comprises a stop plate mounted between the edges of said end plates away from said pole pieces, said stop plate limiting the movement of said armature unit when said coil is deenergized to determine the air gap between said armature and said pole pieces.

9. A miniature relay according to claim 8 wherein said lever arm is shaped so that its end is at a greater distance from said base than said coil to minimize the distance fro-m the base to the coil and permit the actuating of contacts located between the end of said lever arm and said base.

10. A miniature relay according to claim 9 wherein said contacts are mounted at a lesser distance from said coil than the said lever arm and said end plates are mounted in spaced relation to said base at a greater distance than said contacts.

11. An arrangement according to claim 10, wherein said electromagnet unit is hermetically sealed in a cover structure secured to the upper surface of said base and power leads for said means for producing electromagnetic energy and leads to said contacts extend from the other surface of said base.

12. A miniature relay assembly including an electromagnet unit of box-like structure comprising in combination:

(a) a base supporting at least one pair of operating contacts;

(b) first and second end plates supported in spaced relation to said base constructed of magnetic material forming opposite sides of said electromagnet unit and first and second pole pieces projecting respectively from said first and second end plates into the space between them, said pole plates having front and rear faces and upper and lower edges above and below said front and rear faces;

(0) means for providing electromagnetic energy mounted between said end plates, said means comprising a core magnetically connected in series with said end plates and a coil mounted on said core;

(d) a first spacing means constructed of non-magnetic material for maintaining said pole pieces in spaced relation, said first spacing means being positioned so as to leave the front faces of said pole pieces uncovered;

(e) a second means constructed of non-magnetic material mounted to maintain the edges of said end plates remote from said pole pieces in spaced relation;

(f) a substantially L-shaped armature unit comprising an armature and an elongated lever arm having a portion for operating said contacts, said armature having a face for mating with the front faces of said pole pieces; and

(g) means for pivotally supporting said armature unit mounted to a portion of said armature unit intermediate said armature and said elongated lever arm and supporting said armature unit so that said elongated lever arm extends between said base and said electromagnet unit, said armature remaining free of engagement with said pole pieces when said coil is deenergized and defining firstand second air gaps between the face of said armature and the front faces of said first and second pole pieces, said armature unit rotating in response to the flux produced when said coil is energized so that said armature closes the air gaps between said first and second pole pieces to complete the magnetic circuit therebetween and so that said elongated lever arm operates said contacts.

13. An arrangement according to claim 12 wherein the front faces of said pole pieces are formed to have surfaces in a common plane the face of said armature is formed to have a surface in a plane, and said armature is aligned to contact said first and second pole pieces in the common plane when said coil is energized.

14. An arrangement according to claim 13 further comprising means for biasing said armature to one position of angular rotation about said axis comprising a mechanical spring position in the space between said electromagnet unit and said armature.

15. An arrangement according to claim 14 wherein:

(a) said first spacing means comprises a backup plate extending across the space between said pole face pieces and being secured at its ends to the rear faces of said pole pieces and having an aperture formed in its central portion; and

(b) the first leg of said biasing means is flat and rests against said backup plate for preventing rotation of said biasing means and further includes a projection being received in said aperture for retaining said biasing means in place, whereby relative movement between said resilient biasing means and said backup plate is prevented.

16. An arrangement according to claim 15 wherein said pivot support means comprises a U-shaped support constructed of non-magnetic material and having a transverse portion secured to the lower edges of said end plates and first and second arm extending downward- 1y from the ends of said transverse portion, each arm including a bearing, and a non-magnetic shaft secured to a portion of said armature unit intermediate said elongated lever arm and said armature, the ends of said shaft being received in said bearings.

17. An arrangement according to said claim 15 wherein said pivot support means comprises a substantially L- shaped hinge member having a first leg secured to the lower edges of said pole pieces and a second leg secured to said armature unit at a position intermediate said armature and said elongated lever arm, the position of said hinge means being aligned with the space between said pole pieces.

18. A miniature relay including a base supporting at least one pair of operating contacts and an electromagnet unit supported in spaced relation to said base, said electromagnet unit including pole pieces having front faces, said pole pieces being magnetically connected to a source of electromagnetic energy and an armature unit comprising an armature and elongated lever arm for operating said contacts, said armature unit having a face contacting the front face of said pole pieces, said armature unit being pivotally supported so that said armature is free of engagement with said pole pieces when said source is deenergized and moves to close the respective air gaps between the face of said armature and said first and second pole pieces and complete the magnetic circuit therebetween, non-magnetic means secured to said pole pieces and an armature biasing means comprising a non-magnetic mechanical spring positioned between said armature and said non-magnetic means for biasing said armature away from said pole faces.

19. An arrangement according to claim 18 wherein:

(a) said non-magnetic means comprises a backup plate extending across the space between said pole face pieces and being secured at its ends to the rear faces of said pole pieces and having an aperture formed in its central portion; and

(b) the first leg of said biasing means is fiat and rests against said backup plate for preventing rotation of said biasing means and further includes a projection being received in said aperture for retaining said biasing means in place, whereby relative movement between said resilient biasing means and said backup plate is prevented.

20. A miniature relay includin a base supporting at least one movable and one stationary contact and an electromagnet unit supported in spaced relation to said base, said electromagnet unit including pole pieces having front faces, said pole pieces being magnetically connected to a source of electromagnetic energy, and an armature unit comprising an armature and an elongated lever arm for actuating said contacts, said armature unit having a face contacting the front faces of said pole pieces, said armature unit being pivotally supported so that said armature is free of engagement with said pole pieces when said source is deenergized and moves to close the respective air gaps between said armature and said first and second pole pieces and complete the magnetic circuit therebetween, said pivot support means comprises a hinge means consisting of a substantially L-shaped member constructed of non-magnetic material and having a first leg supported to the lower edges of said pole faces and a second leg secured to said armature unit, said armature unit being aligned with respect to said hinge means so that the face of said armature is maintained in spaced relation with said pole faces when said coil is deenergized, said hinge means being deformable in response to the force of said source of electromagnetic energy means on said armature when said coil is energized so that the face of said armature contacts the front faces of said pole pieces.

21. A relay assembly of box-like structure wherein two opposing sides of said structure comprise magnetic material, one of the other sides comprising two magnetic pole pieces each having a planar face portion, a folded armature having a planar face portion of magnetic material cooperating through a respective working air gap with each of the planar face portions of said pole pieces, said armature having an elongated actuating arm extending away from its planar surface portion, at least one pair of operable contacts, means comprising a source of magnetic flux mountedbetween said two opposing magnetic sides for providing a magnetic series circuit for flux flow from said source through one of said pole pieces through one of said working air gaps through the planar face portion of said armature through the other working air gap and the other pole piece to said source, said armature responsive to flow of flux to rotate about an axis extending below the planar face portions of each pole piece and which is-parallel to a line passing through and coplanar with said planar face portions so as to cause the armature to change the respective air gap dimensions identically and to operate said contacts.

22. An arrangement according to claim 21 wherein the faces of said pole piece planar face portions are located in the same plane to insure equal working air gap dimensions with respect to said planar face portion of said armature.

23. An arrangement according to claim 21 comprising means for biasing said armature to one position of angular rotation about said axis, said biasing means comprising a mechanical spring positioned in the space established by the separation of said pole pieces.

24. An arrangement according to claim 23 wherein one end of said mechanical spring is physically constrained in three coordinates in the space established by the separation of said pole pieces and is physically urged by spring tension against the planar face portion of said armature at the other end.

25. An arrangement according to claim 21 further comprising a U-shaped bearing support, a bearing mounted in each of the two arms of said support, and a non-magnetic shaft for rotating said armature in said bearings, said hearing support having its body portion connecting its two extremity arms mounted directly beneath the planar faces of said pole pieces.

26. An arrangement according to claim 21 wherein said contacts are mounted beneath said box-like structure and said armature arm extends beneath said box-like structure to operate said contacts.

27. An arrangement according to claim 26 wherein said box-like structure is hermetically sealed in a square cam, and the power leads for said source and the leads to said contacts extend beneath said box-like structure and out of said can through metal to glass to metal seals.

28. A relay assembly of box-like structure wherein two opposing sides of said structure comprise magnetic material, one of the other sides comprising non-magnetic material, the remaining side comprising two magnetic pole pieces each having a planar face portion separated by a non-magnetic material structure, a folded armature having a planar face portion of magnetic material cooperating through a respective working air gap with each of the planar face portions of said pole pieces, said armature having an elongated actuating arm extending under the box-like structure, at least one pair of operable contacts also supported under said box-like structure, means comprising a source of magnetic flux mounted between said two magnetic opposing sides for providing a magnetic series circuit for flux flow from said source through one pole piece through one of said working air gaps through the planar face portion of said armature through the other working air gap and the other pole piece to said source, said armature responsive to flow of flux to rotate about an axis which is parallel to and magnetically isolated from said two faces of said remaining side, and which is oriented to cause the armature to change the respective air gap dimensions identically.

29. An arrangement according to claim 28 wherein said two pole piece planar face portions are located in the same plane to insure equal working air gap dimensions with respect to said planar face portion of said armature.

30. An arrangement according to claim 28 comprising means for biasing said armature to one position of angular rotation about said axis comprising, said biasing means comprising a mechanical spring positioned in the space established by the separation of said two pole pieces.

31. An arrangement according to claim 30 wherein said mechanical spring physically contacts said non-magnetic material structure at one end of the U and the planar face portion of'said armature at the other end of the U.

32. An arrangement according to claim 28 further comprising a U-shaped bearing support, a bearing mounted in each of the two arms of said support, and a nonmagnetic shaft for rotating said armature planar face portion in said bearings, said bearing support having its body-portion connecting its two arms attached beneath the faces of said pole pieces.

References Cited UNITED STATES PATENTS 3,005,071 10/1961 Brunicardi 335276 3,118,033 1/1964 Somers 335-276 3,154,653 10/1964 Rowell 335276 3,307,127 2/1967 Leo 335128 HAROLD BROOME, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,553,612 Dated 7 January 5, 1971 Inventor) John S. Zimmer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 60, cancel "comprises" and insert comprise Column '7, line 6, cancel "and" and insert said Column 8, line 5 after "second" insert spacing Signed and sealed this 16th day of November 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Acting Commissioner of Patents Atteeting Officer FORM PO-iDSO (\0-69| USCOMM-DC 6037 

